ABSTRACT: Pulmonary arterial hypertension (PAH) is a vascular remodeling disease characterized by enhanced pulmonary artery smooth muscle cell (PASMC) proliferation and suppressed apoptosis. Downregulation of the BMPR2 gene along with activation of the transcription factor NFAT have been implicated in the maintenance of pro-proliferative and anti-apoptotic stages of cells. Since an increasing number of microRNAs have been implicated in the regulation of genes specifically important for cell proliferation and apoptosis, we hypothesized that microRNAs might be associated with these cellular features in the etiology of PAH. We demonstrate that downregulation of one such microRNA (miR-204) in human PAH-PASMC promotes the activation of an Src/STAT3/NFAT axis that increases PAH-PASMC proliferation and their resistance to apoptosis. Stimulation experiments using the pro-PAH factors (PDGF, endothelin-1 and angiotensin II) and time course analysis in experimental PAH show that STAT3 activation leads to miR-204 downregulation, thereby activating an Src-dependent positive feedback loop sustaining STAT3 and activating NFAT. More importantly, restoring miR-204 expression decreases proliferation and resistance to apoptosis in human and in an experimental PAH model. Taken together, our study uncovers a new STAT3-miR-204-Src/STAT3/NFAT axis that links the STAT3-dependent downregulation of BMPR2 with the NFAT-mediated pro-proliferative and anti-apoptotic phenotype observed in PAH. Our data point toward a novel potential strategy for treating patients with PAH. Comparative expression profiling of PAH versus healthy patients to evaluate the modulated genes in the disease. Following the demonstration of the downregulation of miR-204 in PAH we want to investigate the effect of the inhibition (using antagomir) of miR-204 expression in PASMC cells.

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Project description:Pulmonary arterial hypertension (PAH) is a vascular remodeling disease characterized by enhanced pulmonary artery smooth muscle cell (PASMC) proliferation and suppressed apoptosis. Downregulation of the BMPR2 gene along with activation of the transcription factor NFAT have been implicated in the maintenance of pro-proliferative and anti-apoptotic stages of cells. Since an increasing number of microRNAs have been implicated in the regulation of genes specifically important for cell proliferation and apoptosis, we hypothesized that microRNAs might be associated with these cellular features in the etiology of PAH. We demonstrate that downregulation of one such microRNA (miR-204) in human PAH-PASMC promotes the activation of an Src/STAT3/NFAT axis that increases PAH-PASMC proliferation and their resistance to apoptosis. Stimulation experiments using the pro-PAH factors (PDGF, endothelin-1 and angiotensin II) and time course analysis in experimental PAH show that STAT3 activation leads to miR-204 downregulation, thereby activating an Src-dependent positive feedback loop sustaining STAT3 and activating NFAT. More importantly, restoring miR-204 expression decreases proliferation and resistance to apoptosis in human and in an experimental PAH model. Taken together, our study uncovers a new STAT3-miR-204-Src/STAT3/NFAT axis that links the STAT3-dependent downregulation of BMPR2 with the NFAT-mediated pro-proliferative and anti-apoptotic phenotype observed in PAH. Our data point toward a novel potential strategy for treating patients with PAH. Overall design: Comparative expression profiling of PAH versus healthy patients to evaluate the modulated genes in the disease. Following the demonstration of the downregulation of miR-204 in PAH we want to investigate the effect of the inhibition (using antagomir) of miR-204 expression in PASMC cells.

Project description:Squamous cell carcinoma is the second most common skin cancer and frequently progress from an intraepithelial actinic keratosis. The role of microRNAs during the progression from actinic keratosis to cutaneous squamous cell carcinoma (cSCC) remains to be elicited. By using an Agilent microRNA expression microarray we found the expression of miR-204 to be markedly downregulated in cSCC when compared to actinic keratoses. DNA methylation of the TRPM3 promoter region upstream of miR-204-5p was identified as one of the repressive mechanisms that accounts for miR-204 silencing in cSCC. Functional studies on HaCaT cells revealed that this microRNA downregulates the Signal Transducer and Activator of Transcription 3 (STAT3) pathway and favours the MAPK signaling pathway, likely acting through PTPN11, a tyrosine phosphatase that is a direct miR-204 target. We found that activated STAT3, as detected by pY705-STAT3 immunofluorescence, is retained in the membrane and cytoplasm compartment in AK, whereas cSCC displayed STAT3 in the nuclei. Taken together, our data indicates that MiR-204 may act as a “rheostat” that controls the signaling towards the MAPK pathway or the STAT3 pathway. Overall design: 4 samples were analyzed: HaCaT tansduced with control shRNA (n=2) and HaCaT transduced with shRNA against miR-204 (n=2)

Project description:BMPR2 mutation causes pulmonary arterial hypertension (PAH); ACE2 treatment can resolve established BMPR2-mediated PAH. The purpose of this study was to uncover the molecular mechanism behind this. Four groups: +/- ACE2 and +/- BMPR2 transgene, two arrays each, each array a pool of three animals.

Project description:Background: While BMPR2 mutation strongly predisposes to pulmonary arterial hypertension (PAH), only 20% of mutation carriers develop clinical disease. This finding suggests that modifier genes contribute to FPAH clinical expression. Since modifiers are likely to be common alleles, this problem is not tractable by traditional genetic approaches. Further, examination of gene expression is complicated by confounding effects attributable to drugs and the disease process itself. Methods: To resolve these problems, B-cells were isolated, EBV-immortalized, and cultured from familial PAH patients with BMPR2 mutations, mutation positive but disease-free family members, and family members without mutation. This allows examination of differences in gene expression without drug or disease-related effects. These differences were assayed by Affymetrix array, with follow-up by quantitative RT-PCR and additional statistical analyses. Results: By gene array, we found consistent alterations in multiple pathways with known relationship to PAH, including actin organization, immune function, calcium balance, growth, and apoptosis. Selected genes were verified by quantitative RT-PCR using a larger sample set. Analysis of overrepresented gene ontology groups suggests that it is pathway-specific, not gene-specific changes that carry increased risk of disease. Conclusions: B-cell lines are a valuable and accessible tool for assaying alterations in gene expression free from drug and disease effects. Predisposition to disease within BMPR2 mutation carriers was linked to several pathways, including proliferation, GTP signaling, and stress response. Keywords: Search for modifier genes Overall design: Immortalized B-cells from BMPR2 mutation carriers with and without disease are compared to search for modifier genes

Project description:Pulmonary arterial hypertension (PAH) is thought to be driven by dysfunction of pulmonary vascular microendothelial cells (PMVEC). Most hereditary PAH is associated with BMPR2 mutations. However, the physiologic and molecular consequences of expression of BMPR2 mutations in PMVEC are unknown. Overall design: PMVEC were isolated from triple transgenic mice carrying the immortomouse gene, a transactivator, and either control, Bmpr2delx4+ or Bmpr2R899X mutation

Project description:Familial pulmonary arterial hypertension (fPAH) is associated with mutations in BMPR2. Many of these mutations occur in the BMPR2 tail domain, leaving the SMAD functions intact. In order to determine the in vivo consequences of BMPR2 tail domain mutation, we created a smooth-muscle specific doxycycline inducible BMPR2 mutation with an arginine to termination mutation at amino acid 899. When these SM22-rtTA x TetO7-BMPR2R899X mice had transgene induced for 9 weeks, starting at 4 weeks of age, they universally developed pulmonary vascular pruning as assessed by fluorescent microangiography. Approximately half the time the induced animals developed elevated right ventricular systolic pressures (RVSP), associated with extensive pruning, muscularization of small pulmonary vessels, and development of large structural pulmonary vascular changes. These lesions included large numbers of macrophages and T-cells in their adventitial compartment, as well as CD133 positive cells in the lumen. Small vessels filled with CD45 positive and sometimes CD3 positive cells were a common feature in all SM22-rtTA x TetO7-BMPR2R899X mice. Gene array experiments show changes in stress response, muscle organization and function, proliferation and apoptosis, and developmental pathways before RVSP increases. Our results show that the primary phenotypic result of BMPR2 tail domain mutation in smooth muscle is pulmonary vascular pruning leading to elevated RVSP, associated with early dysregulation in multiple pathways with clear relevance to PAH. This model should be useful to the research community in examining early molecular and physical events in the development of PAH, and as a platform to validate potential treatments. Keywords: Disease state analysis Overall design: Each array is an individual female mouse, age-matched, with two mice & arrays used for each of controls (transactivator only), BMPR2-R899X with normal RVSP, and BMPR2-R899X with high RVSP.

Project description:Pulmonary arterial hypertension (PAH) is thought to be driven by dysfunction of pulmonary vascular microendothelial cells (PMVEC). Most hereditary PAH is associated with BMPR2 mutations. However, the physiologic and molecular consequences of expression of BMPR2 mutations in PMVEC are unknown. PMVEC were isolated from triple transgenic mice carrying the immortomouse gene, a transactivator, and either control, Bmpr2delx4+ or Bmpr2R899X mutation